Speed reduction device for a screw-driven power boat



Oct. 5, 1965 R. E. HARTLEY 3,209,716

SPEED REDUCTION DEVICE FOR A SCREW-DRIVEN POWER BOAT Filed Dec. 1, 1964 FIG 3 United States Patent 3,209,716 SPEED REDUCTION DEVICE FOR A SCREW-DRIVEN POWER BOAT Roy E. Hartley, 61-C Ellis St., China Lake, Calif. Filed Dec. 1, 1964, Ser. No. 415,072 3 Claims. (Cl. 114-145) The instant invention relates generally to speed reduction devices, and more particularly to a high-drag device which may be detachably coupled directly to a power unit of a screw-driven power boat and become operative to exert a speed reduction drag on the associated boat when the power unit is operating at preselected speed, preferably idle speeds, i.e., the lowest r.p.m. (revolutions per minute) that may be maintained for the screw of the power unit.

Sport fishermen have long recognized a need for a device which may be utilized with power boats for reducing the speeds thereof sufficiently for fishing while underway, or trolling, at lower speeds, for example, two to four knots. This need has arisen due to the fact that most sport fishermen require a vessel which is large enough and sufiiciently powered for operating at highspeeds normally in excess of twenty knots in large bodies of water in order to meet various government regulations, as well as to be of general utility for recreation purposes.

Presently, the available power units which meet the foregoing requirements are incapable of driving a boat at reduced speeds which accommodate low-speed fishing or trolling operations in shallow waters. This is due to the fact that attainable engine r.p.m. may not be reduced sufiiciently for reducing the rate of screw-rotation to the r.p.m. required for trolling operations. Consequently, various techniques have been employed for inducing drag for thus slowing a power boat in attempting to attain trolling speeds. However, the various means employed are impractical as they serve to foul the screw and/or lines, interfere with motor operations, impair steering, and are manually positioned into and out of operative dispositions. Further, the operations required for positioning the known devices are time consuming, noisy and relatively complicated. Such known techniques and devices include sea-anchors, drag-boards and the like, fixed to a given boat and located in the water. Certain attempts have been made to provide a pivoting plate mounted on a boat and adapted to pivot downwardly into the water to impart the required drag. These devices normally will not accommodate the aforementioned high-speed operations and tend to impairboat-planing and boat-steering characteristics.

The purpose of the instant invention is to provide a drag device for a screw-driven power boat which may be readily fixed to the power unit thereof and left in place throughout all phases of boat operations, and which also serves to enhance boat-planing and boat-steering characteristics, even when the associated boat is operated at the aforementioned high-speeds.

An object of the present invention is to provide a detachable, speed reduction device for a screw-driven power boat which will respond to a given power units output for imposing desired boat speeds on an associated boat.

Another object is to provide a condition-responsive device which will cause the forward motion of a power boat to reduce to a predetermined trolling rate when the boats power unit is caused to operate at predetermined speeds, and which will become substantially inoperative for reducing boat speeds in responsive to an increase in the speed of the power unit and will serve to enhance the boat planing and steering characteristics when the power unit is caused to operate above the predetermined trolling speeds.

Other objects and advantages will become apparent from the following description when considered in conjunction with the accompanying drawing wherein:

FIG. 1 comprises a partial side elevation of that portion of power unit normally disposed below the waterline when the power unit is attached to an operative powerdriven boat, and serves to illustrate the manner in which the device of the instant invention is mounted, as well as alternate extreme operative dispositions therefor;

FIG. 2 comprises a schematic view of a power-driven boat underway, illustrating an operative environment for the device of the instant invention;

FIG. 3 comprises a top plan view illustrating the device of the instant invention in a fully open disposition; and

FIG. 4 comprises a fragmentary bottom plan view illustrating an arrangement of preferred stop means for limiting device opening displacement for the device of FIGS. 1 and 3.

Turning now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 the lower portion of a power unit PU including motor and drive train housing, not designated, a propulsion screw S, and a vertical fin F.

The fin F is normally a thin vertical member disposed in a leading disposition below the screw S. To the fin F is attached the device D of the instant invention.

As more clearly shown in FIGS. 1 and 3, the device D includes a coupling bar 10 having a clevis 11 formed at one end thereof for receiving the vertical fin F. Preferably, the clevis 11 and fin F are drilled to receive pins 12, which extend through the clevis 11 and the fin F and serve for securing the bar 10 to the fin in a horizontally directed disposition beneath the screw S. The bar 10, thus coupled, extends rearwardly with respect to the boat B and parallel the axis of rotation of the screw S. Mounted at the outermost end of the bar 10, opposite the clevis 11, there is a hinge member 13 which is connected with the bar 10, by suitable means, such as, for example, a bar 14 welded to the bar 10 to form a T and coupled with the hinge member 13 by screws 14'. The hinge member 13 is so disposed as to align its axis of rotation transversely with respect to the longitudinal axis of the bar 10 and extends in a generally horizontal plane, transversely with respect to the fin F. The hinge member 13 is further coupled to a flat drag plate 15 through screws 15. The drag plate 15 is dimensioned in a manner such that the drag plate will exert a predetermined retarding force against the power unit for imposing a predetermined drag on the associated boat B when the drag plate is pivotally disposed in an elevated position, as indicated by dotted lines in FIG. 1, and moved forward through the water. Hence it will be appreciated that drag plate 15 is coupled to the bar 10 in a manner such that the plate 15 may be pivoted between an inoperative position, wherein it is disposed in a horizontally and rearwardly directed plane, and an operative position, wherein it is disposed in a vertically and transversely directed plane located directly behind the screw S.

While various spring means may be employed, an adjustable torsion spring 16 has been found suitable for constantly urging the plate 15, in pivotal rotation, into the vertical plane. Since the plate 15 is to be resiliently supported in the vertical plane, or its operative speed reduction position, the forces applied by the spring must be sufficient for overcoming the forces of the water acting against the surface of the plate 15 as the boat progresses through the water. Therefore, the spring 16 is provided with a conventional adjusting means 17 which accommodates an adjustment of the spring constant thereof to effect a change in the resilient forces applied for maintaining the plate in its operative speed reduction position behind the screw S.

It has been found particularly desirable to provide a fixed stop means 18 for supporting the plate 15 in the horizontal inoperative position for limiting the downward pivotal displacement of the plate 15 as the boat B progresses. However, suitable stop means may be included in the hinge member 13, with the stop 18 acting only as an additional stop means. As illustrated, FIG. 4, the stop means 18 comprise a pair of bracket-like members fixed to extend from the bar 14 into the path of the plate 15.

In operation, the device D is assumed to be coupled to the fin F by means of pins or screws 12. In this condition, the plate 15 will 'pivot upwardly, under influence of the spring 16, into engagement with a portion of the power unit, preferably a normally provided bafile plate ./-wfiich extends rearwardly above the screw S. The plate will remain so disposed until it is lowered into the water. Once the screw S and the device D are in the water, the motor may be activated for rotating or driving the screw S. As the screw S is rotated, it forces the surrounding water rearwardly against the plate 15, whereupon the forces of the spring 16 are opposed by the forces of the water displaced by the screw and acting on the surface of the vertically disposed plate 15. Further, the plate 15 acts against its environment as the boat is driven forward through the rotation of the screw S. Consequently, the inertia of the water acting on the plate 15 serves to impose a drag on the boat B for reducing its rate of forward motion. However, as the r.p.m. of the screw S is increased, the dynamic forces applied to the surface of the plate 15, through water being displaced by the screw S, is increased and added to the static forces of the water of the environment. These forces will ultimately attain a value sufficient for overcoming the plate pivoting forces applied by the spring 16, whereupon the plate 15 tends to lay-back against its stops 18 in an inoperative position. In this inoperative position the boat may attain a forward motion substantially unhampered by the device D. It is here noted that it is postulated that the energy required for maintaining the plate 15 in its inoperative speed reduction position is derived from the water displaced by the screw S, since no substantial loss of boat speed is in practice encountered once the plate 15 attains its horizontal inoperative position.

As the boat progresses through the water, with the plate 15 in an inoperative position, the boat tends to plane, due in part to the effects of the extended plate 15, and as turns are executed, one side of plate 15 is raised while the other side is depressed, whereby the characteristics of a vertical fin are imparted to the plate 15 which serve to enhance the steering characteristics of the boat B.

In order to reduce the forward motion of the boat, it is necessary to merely reduce the r.p.m. of the screw S, whereupon the recovery forces of the spring 16 tend to overcome the forces applied through the water against the plate 15. As the spring forces overcome the forces applied to the plate through the water, the plate 15 is pivoted in a vertical direction to once again imposed a drag on the boat B.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practical otherwise than specifically described.

I claim:

1. A speed reduction device to be connected with a boat-mounted power unit of the type which includes an engine, an engine driven screw, and a vertical fin disposed below the screw in a leading relationship therewith, and adapted to reduce the forward motion of the associated boat to a rate substantially below that obtainable at power unit idle-speeds, and which may be rendered ineffective for reducing forward motion by increasing the speed of the power unit to a speed substantially above idle-speeds, comprising in combination:

an elongated coupling bar;

20 coupling means adapted to couple said bar with the vertical fin of the power unit in a manner such that the bar is caused to extend in a horizontal direction from said fin parallel and beneath the rotational axis of the screw;

a flat rectangular plate having a preselected surface.

area;

a coupling hinge member mounted at the outermost end of the extended bar and serving to couple the plate with the outermost end of the bar in a manner such that the plate may be pivoted between a lowdrag position in a horizontally directed plane and a high-drag position in a vertically directed plane disposed behind the screw and extending across the axis of rotation of said screw;

a spring member mounted on said hinge member adapted to constantly apply a predetermined pivoting force to said plate for constantly urging said plate into the vertical plane, whereby the plate may be maintained in a high-drag speed reduction position in the vertical plane under the influence of said spring when said power unit is operating at idle speeds, and maintained in a low-drag position-in the horizontal plane under the influence of the forces of water acting thereon when said power unit is operating at speeds above idle speeds.

2. The device of claim 1, wherein the coupling meansincludes a clevis formed at one end of the coupling bar.

3. The device according to claim 2, further characterized in that said spring member comprises an adjustable torsion spring, whereby the pivoting force applied to said plate may be selectively varied.

References Cited by the Examiner UNITED STATES PATENTS 2,719,503 10/55 Smith ll4-145 X 3,136,280 6/64 Bergum 114-145 X MILTON BUCHLER, Primary Examiner. ANDREW FARRELL, Examiner. 

1. A SPEED REDUCTION DEVICE TO BE CONNECTED WITH A BOAT-MOUNTED POWER UNIT OF THE TYPE WHICH INCLUDES AN ENGINE, AN ENGINE DRIVEN SCREW, AND A VERTICAL FIN DISPOSED BELOW THE SCREW IN A LEADING RELATIONSHIP THEREWITH AND ADAPTED TO REDUCE THE FORWARD NOTION OF THE ASSOCIATED BOAT TO A RATE SUBSTANTIALLY BELOW THAT OBTAINABLE AT POWER UNIT IDLE-SPEEDS, AND WHICH MAY BE RENDERED INEFFICTIVE FOR REDUCING FORWARD MOTION BY INCREASING THE SPEED OF THE POWER UNIT TO A SPEED SUBSTANTIALLY ABOVE IDLE-SPEEDS, COMPRISING IN COMBINATION: AN ELONGATED COUPLING BAR; COUPLING MEANS ADAPTED TO COUPLE SAID BAR WITH THE VERTICAL FIN OF THE POWER UNIT IN A MANNER SUCH THAT THE BAR IS CAUSED TO EXTEND IN A HORIZONTAL DIRECTION FROM SAID FIN PARALLEL AND BENEATH THE ROTATIONAL AXIS OF THE SCREW; A FLAT RECTANGULAR PLATE HAVING A PRESELECTED SURFACE AREA; A COUPLING HINGE MEMBER MOUNTED AT THE OUTERMOST END OF THE EXTENDED BAR AND SERVING TO COUPLE THE PLATE WITH THE OUTERMOST END OF THE BAR IN A MANNER SUCH THAT THE PLATE MAY BE PIVOTED BETWEEN A LOWDRAG POSITION IN A HORIZONTALLY DIRECTED PLANE AND A HIGH-DRAG POSITION IN A VERTICALLY DIRECTED PLANE DISPOSED BEHIND THE SCREW AND EXTENDING ACROSS THE AXIS OF ROTATION OF SAID SCREW; A SPRING MEMBER MOUNTED ON SAID HINGE MEMBER ADAPTED TO CONSTANTLY APPLY A PREDETERMINED PIVOTING FORCE TO SAID PLATE FOR CONSTANTLY URGING SAID PLATE INTO THE VERTICAL PLANE, WHEREBY URGING SAID PLATE MAINTAINED IN A HIGH-DRAG SPEED REDUCTION POSITION IN THE VERTICAL PLANE UNDER THE INFLUENCE OF SAID SPRING WHEN SAID POWER UNIT IS OPERATING AT IDLE SPEEDS, AND MAINTAINED IN A LOW-DRAG POSITION IN THE HORIZONTAL PLANE UNDER THE INFLUENCE OF THE FORCES OF WATER ACTING THEREON WHEN SAID POWER UNIT IS OPERATING AT SPEEDS ABOVE IDEL SPEEDS. 